From fc3faab5f1f1593c25ca72ee0831f95f0f43e222 Mon Sep 17 00:00:00 2001
From: Alexander Bock <alexander.bock@liu.se>
Date: Thu, 28 May 2015 20:33:22 +0200
Subject: [PATCH] Replace commandline argument with automatically detecting the
 supported OpenGL version

---
 include/openspace/engine/openspaceengine.h |  2 +-
 src/engine/openspaceengine.cpp             | 15 +-------
 src/main.cpp                               | 44 ++++++++++++++--------
 3 files changed, 31 insertions(+), 30 deletions(-)

diff --git a/include/openspace/engine/openspaceengine.h b/include/openspace/engine/openspaceengine.h
index 11f1eee190..08a25948d9 100644
--- a/include/openspace/engine/openspaceengine.h
+++ b/include/openspace/engine/openspaceengine.h
@@ -59,7 +59,7 @@ namespace scripting {
 
 class OpenSpaceEngine {
 public:
-    static bool create(int argc, char** argv, std::vector<std::string>& sgctArguments, std::string& openGlVersion);
+    static bool create(int argc, char** argv, std::vector<std::string>& sgctArguments);
     static void destroy();
     static OpenSpaceEngine& ref();
 
diff --git a/src/engine/openspaceengine.cpp b/src/engine/openspaceengine.cpp
index 7197d9249d..d38555a20e 100644
--- a/src/engine/openspaceengine.cpp
+++ b/src/engine/openspaceengine.cpp
@@ -96,7 +96,6 @@ namespace {
     struct {
         std::string configurationName;
 		std::string sgctConfigurationName;
-        std::string openGlVersion;
     } commandlineArgumentPlaceholders;
 }
 
@@ -148,8 +147,7 @@ OpenSpaceEngine& OpenSpaceEngine::ref() {
 
 bool OpenSpaceEngine::create(
     int argc, char** argv,
-    std::vector<std::string>& sgctArguments,
-    std::string& openGlVersion)
+    std::vector<std::string>& sgctArguments)
 {
     ghoul::initialize();
 
@@ -260,10 +258,6 @@ bool OpenSpaceEngine::create(
 		sgctConfigurationPath = commandlineArgumentPlaceholders.sgctConfigurationName;
 	}
 
-    openGlVersion = commandlineArgumentPlaceholders.openGlVersion;
-    if (openGlVersion != DefaultOpenGlVersion)
-        LINFO("Using OpenGL version " << openGlVersion);
-
 	// Prepend the outgoing sgctArguments with the program name
 	// as well as the configuration file that sgct is supposed to use
 	sgctArguments.insert(sgctArguments.begin(), argv[0]);
@@ -401,13 +395,6 @@ bool OpenSpaceEngine::gatherCommandlineArguments() {
 		"the OpenSpace configuration file");
 	_commandlineParser->addCommand(sgctConfigFileCommand);
 
-    commandlineArgumentPlaceholders.openGlVersion = DefaultOpenGlVersion;
-    CommandlineCommand* openGlVersionCommand = new SingleCommand<std::string>(
-        &commandlineArgumentPlaceholders.openGlVersion,
-        "-ogl", "-o",
-        "Sets the OpenGL version that is to be used; valid values are '4.2' and '4.3'");
-    _commandlineParser->addCommand(openGlVersionCommand);
-
     return true;
 }
 
diff --git a/src/main.cpp b/src/main.cpp
index 7adc2126a2..117e7d435f 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -47,6 +47,21 @@ void mainDecodeFun();
 void mainExternalControlCallback(const char * receivedChars, int size);
 void mainLogCallback(const char* msg);
 
+std::pair<int, int> supportedOpenGLVersion () {
+    glfwInit();
+    glfwWindowHint(GLFW_VISIBLE, GL_FALSE);
+    GLFWwindow* offscreen = glfwCreateWindow(128, 128, "", nullptr, nullptr);
+    glfwMakeContextCurrent(offscreen);
+
+    int major, minor;
+    glGetIntegerv(GL_MAJOR_VERSION, &major);
+    glGetIntegerv(GL_MINOR_VERSION, &minor);
+
+    glfwDestroyWindow(offscreen);
+    glfwWindowHint(GLFW_VISIBLE, GL_TRUE);
+    return { major, minor };
+}
+
 //temporary post-FX functions, TODO make a more permanent solution to this @JK
 void postFXPass();
 void setupPostFX();
@@ -60,13 +75,13 @@ namespace {
 }
 
 int main(int argc, char** argv) {
+    auto glVersion = supportedOpenGLVersion();
+    
     // create the OpenSpace engine and get arguments for the sgct engine
     std::vector<std::string> sgctArguments;
-    std::string openGlVersion = "";
     const bool success = openspace::OpenSpaceEngine::create(
         argc, argv,
-        sgctArguments,
-        openGlVersion
+        sgctArguments
     );
     if (!success)
         return EXIT_FAILURE;
@@ -115,21 +130,20 @@ int main(int argc, char** argv) {
 
     // try to open a window
     LDEBUG("Initialize SGCT Engine");
-#ifdef __APPLE__
-    sgct::Engine::RunMode rm = sgct::Engine::RunMode::OpenGL_4_1_Core_Profile;
-#else
-    std::map<std::string, sgct::Engine::RunMode> versionMapping = {
-        { "4.2", sgct::Engine::RunMode::OpenGL_4_2_Core_Profile },
-        { "4.3", sgct::Engine::RunMode::OpenGL_4_3_Core_Profile },
-        { "4.4", sgct::Engine::RunMode::OpenGL_4_4_Core_Profile },
-        { "4.5", sgct::Engine::RunMode::OpenGL_4_5_Core_Profile }
+    std::map<std::pair<int, int>, sgct::Engine::RunMode> versionMapping = {
+        { { 3, 3 }, sgct::Engine::RunMode::OpenGL_3_3_Core_Profile },
+        { { 4, 0 }, sgct::Engine::RunMode::OpenGL_4_0_Core_Profile },
+        { { 4, 1 }, sgct::Engine::RunMode::OpenGL_4_1_Core_Profile },
+        { { 4, 2 }, sgct::Engine::RunMode::OpenGL_4_2_Core_Profile },
+        { { 4, 3 }, sgct::Engine::RunMode::OpenGL_4_3_Core_Profile },
+        { { 4, 4 }, sgct::Engine::RunMode::OpenGL_4_4_Core_Profile },
+        { { 4, 5 }, sgct::Engine::RunMode::OpenGL_4_5_Core_Profile }
     };
-    if (versionMapping.find(openGlVersion) == versionMapping.end()) {
-        LFATAL("Requested OpenGL version " << openGlVersion << " not supported");
+    if (versionMapping.find(glVersion) == versionMapping.end()) {
+        LFATAL("Requested OpenGL version " << glVersion.first << "." << glVersion.second << " not supported");
         return EXIT_FAILURE;
     }
-    sgct::Engine::RunMode rm = versionMapping[openGlVersion];
-#endif
+    sgct::Engine::RunMode rm = versionMapping[glVersion];
     const bool initSuccess = _sgctEngine->init(rm);
     if (!initSuccess) {
         LFATAL("Initializing failed");